Medicines and pharmaceutical substances are generally manufactured in tablet or capsule form in pre-determined dosages chosen from a relatively limited range, based on the presumptions of the manufacturer as to what dosages are likely to be prescribed by physicians for a majority of their patients. Without a flexible range of doses being is available, the patient is forced to break tablets in half, or to remember complicated dosing schedules, such as having to take two tablets on Mondays, Wednesdays and Fridays, and three tablets on all other days of the week. Because each patient is different, such predetermined dosages are almost invariably an approximation or a compromise relative for what the patient actually needs.
For example, certain psychotropic medications such as lithium carbonate (used to treat bipolar illness) are safe and effective only within a relatively narrow range of dosages based on a variety of factors including the patient's age, body weight, drug elimination rate, general health, and tolerance to the particular medication prescribed. If the dosage is too low, as reflected by the concentration of the medication in the patient's blood, its threshold of effectiveness may not have been reached and the patient will enjoy no benefits. On the other hand, if the dosage is too high, while the patient may be relieved of his or her symptoms, serious symptoms of toxicity or other intolerance to the medication may result.
Other situations in which a variable, continuously adjustable dose would be of benefit to both the prescribing physician and the patient include dosage adjustment based on serum or plasma concentration of drugs having a relatively narrow therapeutic window, such as (for example) theophylline, digoxin, and many anticonvulsants, including phenobarbital and dilantin, as well as drugs with a variable and unpredictable patient response such as the immunosuppressants methotrexate, prednisone and cyclosporine.
The invention is of particular benefit to the practice of veterinary medicine, in which the physician encounters wide extremes of size and species. It also benefits research pharmacists who are required to prepare small batches of capsules with various fillers for purposes of stability testing, analytical assay, reference material, clinical trials and dissolution studies.
For these reasons it would be highly advantageous if the prescribing physician could be able to prescribe medications in filled capsules which are individually tailored to the needs of each patient in terms of both type of medication (including combinations of drugs) and dosage. For this purpose, the present invention provides a capsule filling device capable of filling capsules with any filler material, particularly dry flowable powdered or micro-encapsulated medication in any dosage desired. In addition, it allows for filling individual groups of capsules with specific doses of one or more medications.
The prior art includes a variety of capsule filling devices and methods of operation which accomplish the task of measuring and distributing dry flowable medications into individual capsules. One example is U.S. Pat. No. 5,797,248 which discloses a manual capsule filling device in which a known quantity of dry material, such as from a bottle in which the weight of the contents is known, is emptied into a reservoir which overlies a rotary dosage plate containing a plurality of spaced cavities, each cavity being of a known volume. The medication is allowed to flow into and fill the cavities, whereupon the dosage plate is rotated to transfer its contents into individual capsules below. The capsules are then capped and replaced by empty capsules, and the operation is repeated as many times as is necessary to fill the required number of capsules.
However, this system has several disadvantages, such as the inability to fill capsules by weight instead of volume, and the inability to change the dosage without emptying the device and changing the dosage plate.
Another manual capsule filling device is shown in U.S. Pat. No. 5,660,029 in which is empty capsules are placed in cavities in a funnel-shaped tray. A known quantity of medication is placed in the tray and raked or swept into the capsule, such as by tilting or tapping the tray, after which the capsule contents are compressed by tamping before the capsule is capped. The tamping tool is also useable to remove the filled capsules from their cavities.
Mentioned in U.S. Pat. No. 5,797,248 are other examples of similar prior art. Canadian Patent 494,695 shows a capsule filling device in which a measured amount of pharmaceutical is placed on a spreader plate with wells, the depth of the wells being adjustable. The pharmaceutical is spread into the wells until it is flush with the tops of the wells, the spreader plate is covered with a funnel system and turned upside down to allow the dry medication to funnel into the capsules. U.S. Pat. No. 5,321,932 shows a device to open and close capsules so that they may be filled, however, the method of filling the capsules is not described. U.S. Pat. No. 4,619,336 provides a method and apparatus for weighing doses of powder in which powder is fed onto a weigh scale which stops the powder flow just below the desired weight, at which point remaining powder is allowed to run into the weighing receptacle.
Highly mechanized devices for filling capsules in mass production are also shown in the prior art, such as U.S. Pat. Nos. 6,170,226, 5,490,702, 5,018,335 and 4,964,262, and 4,731,979, but all of these machines lack the flexibility and adaptability of the present invention because they depend on a mechanical or pneumatic charging system which must be re-set, re-calibrated and re-tested every time a new and different batch of capsules is run.